During CABG, total peroxide (TP) and oxidative stress index approximately double Increased post-bypass plasma levels of inflammatory markers such as C-reactive protein (CRP) and platelets and leukocyte activation have been observed during CPB. Increases in oxidative stress associated with CPB are correlated with a reduction in total plasma antioxidant capacity. These observations are of interest because an antioxidant is a molecule that inhibits the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When the chain reaction occurs in a cell, it can cause damage or death to the cell. Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions by auto-oxidation; hence antioxidants are often reducing agents. The investigators propose that cell damage induced by oxidative stress and I/R injury could be prevented and/or inhibited by antioxidant supplementation. Specifically the investigators hypothesize that high-dose intravenous (IV) vitamin C supplementation will ameliorate ROS and therefore damp down upstream inflammatory processes, leading to a reduction of downstream adverse events with demonstrable links to inflammation processes, such as AF. Vitamin C is an viable therapeutic candidate because it is a powerful antioxidant with an excellent safety profile, and an emerging history of reducing inflammatory markers in both critically ill and traumatically injured patients. Scattered trials have indicated possible benefits of vitamin C in reducing incidence of post-CABG AF (see Literature search). An antioxidant such as vitamin C acts as a scavenger of intracellular oxidant species; as these are essential mediators in eicosanoids synthesis pathways, it is expected that vitamin C supplementation would decrease the thrombotic potential of eicosanoid-mediated pathways, such as the thromboxane (TBX) production pathway. Impaired cardiac blood flow and clot formation associated with AF contributes to congestive heart failure and stroke; therefore reduction of thrombotic potential is another essential feature for the proposed therapeutic agent.